Particle separator: removing particles from stormwater

01What is a particle separator?

A particle separator is a buried storage volume that receives stormwater from impermeable surfaces and lets the particles settle to the bottom by sedimentation. Sand, silt and sediment are held back, while the cleaner water is carried onward. WaterCare's particle separators are sand traps optimised for higher stormwater volumes, so that the separation holds even during heavy rainfall. Norrloop supplies them in rotationally moulded polyethylene (PE).

02Not to be confused with a sludge separator for heating/cooling systems

The term particle separator is sometimes confused with a sludge separator for heating/cooling systems. These are two different things. A sludge separator for heating/cooling systems removes sludge and magnetite in indoor heating and cooling systems. A particle separator here is about outdoor stormwater: rainwater from roads, car parks and industrial surfaces that is to be cleaned of particles before it is infiltrated or discharged.

03Why must stormwater be cleaned of particles?

Stormwater from trafficked surfaces carries sand, sediment and pollution that is bound to the particles. Two reasons to remove it:

• Sediment clogs infiltration systems and soakaways and reduces their service life
• Particles and particle-bound pollution burden streams, watercourses and lakes downstream

Many local authorities therefore require that stormwater from roads and parking is cleaned before it is infiltrated or released to a receiving water.

04Particle separator or ordinary sand trap?

The two are related, but sized for different loads:

Norrloop sizes the right solution based on the area, the rainfall and where the water goes next.

05Where is it placed in the system?

The particle separator is placed early in the stormwater line, before infiltration, attenuation or discharge. The particles are then captured before they reach and clog the downstream parts:

06Operation and emptying

The sediment collects at the bottom of the separator and is removed by emptying. How often depends on how much particle load the surface adds. Regular inspection and emptying ensure that the separation holds, and that sediment is not carried onward in the system. Access to the chamber and lid makes maintenance easy.

07Why a particle separator in PE?

Particle separators in polyethylene are corrosion-free, watertight and easy to handle. PE withstands the moist soil environment over a long period without sacrificial anodes or risk of rust, and can be adapted to different system sizes.

08Frequently asked questions